Repeated use of a punch assembly in a punch press operation results in the natural dulling and wear of the punch tip. Once the tip has become dull, the effectiveness of the punch assembly is reduced and the punch tip must be sharpened. Sharpening may be accomplished by grinding the end of the punch tip, and this results in shortening the length of the punch. The length of the punch then must be adjusted to compensate for the ground-off portion.
Punch assemblies that allow for length corrections are exemplified in U.S. Pat. No. Re 29,958. This reference compensates for the lost punch length by adding washers or other similar objects to the punch. The problem with this method is that the added washers or the like are usually weak and cannot withstand the constant cyclical forces placed upon a punch. Also, the length of the punch tip can only be adjusted within certain limits before it becomes too short for effective operation, thereby limiting the number of times the punch tip can be sharpened.
Most known methods that allow for the adjustment of the length of the punch tip require dismantling of the entire punch in order to access the punch tip for adjustment this obviously can be a rather time consuming process. Additionally, once the punch has been reassembled further effort is frequently expended in determining how much the sharpening and adjusting steps have affected the position of the tip. A need exists, therefore, for an accurate means of adjusting the length of the punch in a manner that is not overly time consuming or difficult.